Detection op possibly erroneous segments following
failures in primary storage

ABSTRACT

A METHOD FOR DETECTING POSSIBLY ERRONEOUS MEMORY SEGMENTS IN A HIERARCHICAL MEMORY SYSTEM HAVING AT LEAST A PRIMARY AND SECONDARY BACK-UP MEMORY FOLLOWING FAILURE IN THE PRIMARY STORAGE OF SAID SYSTEM. THE METHOD GENERALLY INCLUDES KEEPING CERTAIN STATISTICAL DATA CONCERNING THE TRANSFER OF DATA SEGMENTS INTO AND OUT OF SAID PRIMARY STORAGE WHEREBY AUTOMATIC VALIDITY CHECKING PROCEDURES CAN BE PERFORMED TO DETERMINE THE PROBABLE ACCURACY OF THE CURRENT CONTENTS OF SAID PRIMARY MEMORY.

DEFENSIVE PUBLICATION UNITED STATES PATENT AND TRADEMARK OFFICE Published at the request of the applicant or owner in accordance with the Notice of Dec. 16.1969, 869 0.G. 687. The abstracts of Defensive Publication applications are identified by distinctly numbered series and are arranged chronologically. The heading of each abstract indicates the number of pages of specification, including claims and sheets of drawings contained in the application as originally filed. The files of these applications are available to the pu c inspection and reproduction may be purchased for 30 cents a sheet.

Defensive Publication applications have not been examined as to the merits of alleged invention. The Patent and Trademark Oflicc makes no assertion as to the novelty of the disclosed subject matter.

PUBLISHED MARCH 4:, 1975 932 QG. 1O

DETECTION OF POSSIBLY ERRONEOUS SEG- MENTS FOLLOWING FAILURES IN PRIMARY STORAGE Vincent J. Krnskal, Ossining, N. asslgnor to International Business Machines Corporation, Armonk, N.Y. Filed Dec. 28, 1973, Ser. No. 429,303 Int. Cl. G06f 11/06; Gllc 29/00 US. Cl. 235-153 AM 15 Sheets Drawing. 23 Pages Specification PROCESSOR fifl I? SECONDARY PRIMARY BACK- p STORAGE STORAGE (Le. DISK) 0B 1 l 16 FAILURE SEGMENT TABLE ADDRESS TABLE FAILURE COUNT DETECTION REGISTERS CQ R A method for detecting possibly erroneous memory segments in a hierarchical memory system having at least a primary and secondary back-up memory following failure in the primary storage of said system. The method generally includes keeping certain statistical data concerning the transfer of data segments into and out of said primary storage whereby automatic validity checking procedures can be performed to determine the probable accuracy of the current contents of said primary memory.

Mach 4, 1975 v. J. KRUSKAL T9329 DETECTION OF POSSIBLY EHRONEOUS SEGMENTS FQLLOWING FAILURES IN PRIMARY STORAGE Filed Dec. 28, 1973 15 Sheets-Sheet 1 PROCESSOR FIG. 1

12 SECONDARY PRIMARY BACK UP STORAGE STORAGE (Le. DISK) FAILURE SEGMENT TABLE ADDRESS TABLE L FAILURE COUNT DETECTION REGISTERS E CONTROL March 4, 1975 v. J. KRUSKAL P9329005 DETECTION OF POSSIBLY EHRONEDUS SEGHENTS FOLLOWING FAILURES IN IRIMARY STORAGE Filed Dec. 28. 1973 15 Sheets-Sheet 2 F I G. 2A FIG. 2

SYSTEM PROGRAM MAKES DECISION S TO TRANSFER SEGMENT FROM 2 SECONDARY T0 PRIMARY STORE.

FIG. 28

FIG.

2C SYSTEM PROGRAM LOADS REGEIOO WITH STARTING ADDRESS OF SEGMENT HG IN PRIMARY STORE mus IS ADDRESS 20 0F HEADER WORD THAT CONTAINS THE TIME AND IOTA COUNT) SYSTEM PROGRAM ACCOMPLISHES TRANSFER OF SEGMENT FROM SECONDARY TO PRIMARY STORE MICROPROGRAM GATES REG. IOO

MICROPROCRAM REQUESTS READ ACCESS OF PRIMARY STORE READ ACCESS OF PRIMARY STORE MICROPROGRAM GATES $454 REC. I04 TO REOIS I March 4, 1975 DETECTION OF Filed Dec. 28. 1973 FIG. 28

V. J. KRUSKAL POSSIBLY EHRONEOUS SEGMENTS FOLLOWING FAILURES TN PRIMARY STORAGE l5 Sheets-Sheet 5 MICRDPRDGRAM TESTS BIT T22 IN REG. 104

BIT T22=1 SETS FF.

MICROPROCRAM GATES CTR. 112 TO REC. H8

CTR. H2 TO RECHA MICRDPROGRAM REQUESTS READ ACCESS OF CORE SECONDARY STORAGE 138 READ ACCESS WHEN ACCESS IS COMPLETED MICROPROCRAM TESTS COMPARE UNIT 24 f seg "r crash I -r seg 1 crash ADDRESS MTCROPROGRAM DECREMENTS MICROPRDCRAM GATES CTRHZ TD RECHO March 4, 1975 V. J. KRUSKAL DETECTION OF POSSIBLY ERRONEOUS SEGHEXTS FOLLOWING FAILURES IN PRIMARY STORAGE Filed Dec. 28, 1973 15 Sheets-Sheet 4 FIG.2C

MICROPROCRAM INCREMENTS CTR, H2

MICROPROGRAM GATES CTR H2 TO RECHD MICRDPROGRAM REQUESTS READ ACCESS DF CORE SECONDARY STORAGE READ ACCESS REQUEST WHEN ACCESS IS COMPLETED MICROPROGRAM SETS RE. 128 TO "1" GATES REC. H4 TO REG. H2

MICROPRDGRAM TESTS COMPARE UNIT T24 w' crosh i seg w crosh i seg Much 4, 1975 v. J. KRUSKAL T932905 DETECTION OF POSSIBLY ERRDNEOUS SEGMBNTS FOLLOWING FAILURES IN PRIMARY STORAGE Filed Dec. 28, 1973 1.5 Sheets-Sheet 5 FIG. 2D

MICROPROGRAM SETS MICROPROGRAM sers an 122 T0 "i" ms T22 AND 132 M'CROPROGRAM GATES MTCROPROGRAM SIGNALS IOTA COUNT FROM "PREMATURE SEGMENT" mus T0 REG.T34

MICROPROCRAM GATES \{86 REC.134 T0 REG.T04

MICROPRCCRAM TNCREMENTS RECMB REQUESTS WRITE ACCESS OF PRIMARY STORE WRiTE ACCESS REQUEST WHEN ACCESS IS COMPLETED MTCROPROCRAM SIGNALS "SEGMENT INPUT DONE" March 4. 1975 v. J. KRUSKAL T932905 DETECTION OF POSSIBLY ERRONEOUS SEGMENTS FOLLOWING FAILURES IN PRIMARY STORAGE Filed Dec. 28, 1973 15 Sheets-Sheet 5 MICROPROGRAM G/ 220 GATES REG. 154 E0 REG. 104

FIG. 3C

MICROPROGRAM 222 REQUESTS WRITE AGGEss 0F PR1 MARY STGRE WHEN ACCESS IS COMPLETE SYSTEM PROGRAM TRANSFERS SEGMENT ERGM PRIMARY TO SECONDARY STORE H G 3 SYSTEM PROGRAM SIGNALS "SEGMENT TRANSFER FIG. DONE FIG. 38

March 4, 1975 v. .1. KRUSKAL T932305 DETECTION OF POSSIBLY ERRONEOUS SEGMENTS FOLLOWING FAILURES IN PRIMARY STORAGE Filed Dec. 28, 1973 15 Sheets-Sheet 7 F I G 3A l SYSTEM PROGRAM MAKES DECISION TO TRANSFER SEGMENT FROM PRIMARY TO SECONDARY STORAGE MICROPROGRAM RESEIS CTR. J /200 SETS REG. I36 TO 11 ----11 SETS EE I30 T0 "1" MICROPROGRAM GATES STARTING ADDRESS TO 202 REG. 102

MIOROPROGRAM A/204 REQUESTS READ ACCESS OF PRIMARY STORE WHEN READ ACOESSOF PRIMARY STOR IS COMPLETED MIGROPROGRAM 206 GATES REG. 104 TO REG. 154

MICROPROGRAM J08 TESTS COMPARE umr I24 /REGv 134 REGEISS REO.134 REOISB Much 4, 1975 v. .1. KRUSKAL T932,005

DETECTION OF POSSIBLY EHRONEOUS SEGHENTS FOLLOWING FAILURES IN PRIMARY STORAGE Filed Doc. 28, 1973 15 Sheets-Sheet 8 /RE[;, I34 REG. 15s WREG. 4 RE 156 GATE REG 134 TO REG. I36 2IO MIGROPROGRAM 212 INGREMENTS CTR J MIOROPROGRAM 214 TESTS CTRJ MICROPROGRAM GATES REG. 156 T0 OMEGA m comm REGIOB SYSTEM PROGRAM LOADS REOIOO WITH STARTING ADDRESS OF SEGMENT IN PRIMARY STORE. (THIS IS ADDRESS OF HEADER WORD THAT CONTAINS THE TIME AND IOTA COUNT) MIOROPROGRAM GATES REG. IOO TO REGIOZ GATES TIME IN REG I06 TO REGI34 GATES IOTA COUNT IN REG.

116 TO REGI34 RESETS F F 122 TO "0" Much 4, 1975 v. J KRUSKAL DETECTION OF POSSIBLY ERRONEOUS SEGIENTS FOLLOWING FAILURES IN PRIMARY STORAGE Filed Dec. 28, 1973 FIG.4

l5 Sheets-Shoat 9 WHEN STARTING AGAIN AFTER A SYSTEM CRASH MICROPROGRAM INCREMENTS THE ADDRESS CTR. 112

GATES OMEGA COUNT IN REGIOB TO RIGHT HALF OF REGIIO MICROPROGRAM REQUESTS WRITE ACCESS 0F GORE SEC. STORE COMPLETED WHEN WRITE ACCESS 0F CORE SEC, STORE IS SYSTEM PROGRAM CONTINUES v. J. KRUSKAL T932,005 F POSSIBLY BRRQNEOUS SEGIENTS FOLLOWING FAILURES IN PRIMARY STU March 4, 1975 RAGE DETECTION 0 Filed Dec. 28, 1973 15 Sheets-Sheet X0 LQOE wmdE QQQI omdE mmdE 4nd;

LLOWING l5 Sheets-Sheet 1 l Mar'lh 1975 v. J. KRUSKAL DETECTION OF POSSIBLY ERRONEOUS SEGIENTS F0 FAILURES IN PRIMARY STORAGE Filed Dec. 28. 1973 V w i y n N: 02 E k 28 3mg? 0 6: N mo 7 y W O? m f 1!! N2 v $02 332 E me E; 2: E25 mwobm E8 525 1 o ME v E o @352 m0 E w r w:

March 4, 1975 v. J. KRUSKAL T9329 DETECTION OF POSSIBLY ERRONEOUS SEGIENTS FOLLOWING FAILURES IN PRIMARY STORAGE 15 Sheets-Sheet 12 Filed Doc. 28. 1973 wow 1* mo o E It: mm: n 2N mo 32 2: E 525 1 am mo 52 E; 5565 E 522E. 2T E5 mmdI March 4, 1975 v J. KRUSKAL T932,005

POSSIBLY EHRONEOUS SEGIIENTS FOLLOWING DRAG! DETECTION OF FAILURES IN PRIMARY ST Filed Doc. 28, 1973 15 Sheets-Sheet 15 oe 7 8T .35 c 1 J NON 225 is; a 522 M 0m 0; 0 :1 J \llkflllib) NON 3 8 2m 8 8 0 N m w m mmooomc wwww v. J. KRUSKAL T932,005 DETECTION OF POSSIBLY ERRONEOUS SEGIENTS FOLLOWING Much 4, 1975 FAILURES IN PRIMARY STORAGE 15 Sheets-Sheet 1 4 Filed Dec. 28. 1973 w 5E v; Q:

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